The proposed training program is the centerpiece in efforts to provide postdoctoral training in laboratory genetics for medical geneticists at Harvard Medical School (HMS) and its affiliated institutions. This program has made possible the opportunity to offer training to physicians and scientists in a wide variety of disciplines, enabling them to take advantage of the extraordinarily rich academic environment offered at HMS and its affiliated institutions. It has also helped promote interactions between investigators and provided a forum for increasing faculty contact with trainees in didactic sessions. The training units of the program include laboratories at the HMS Department of Genetics, Beth Israel Deaconess Medical Center (BIDMC), Brigham and Women's Hospital (BWH), Children's Hospital (CH), Dana Farber Cancer Institute (DFCI) and Massachusetts General Hospital (MGH). The focus of the training is on research in medical genetics, and the program is fully integrated with the HMS American Board of Medical Genetics (ABMG) training program, which is accredited by the ABMG in all areas of training (M.D. Clinical Genetics, Ph.D. Medical Genetics, Cytogenetics, Biochemical Genetics, and Molecular Genetics). This provides the opportunity for trainees to become active candidates for the certification examinations in a discipline(s) of medical genetics in addition to receiving laboratory training. Fellowship training is provided for two to three years, and support for ten postdoctoral trainees is requested. Since the last renewal of this training grant The Harvard Partners Center for Genetics and Genomics has been initiated. HPCGG is a cooperative effort and represents a major investment and focus in medical genetics at Harvard. The HMS Training Grant in Genetics is an integral component in accomplishing the HPCGG goal of training the next generation of medical geneticists and represents one of the Center's major educational opportunities.